A number of systems have been suggested heretofore for an automotive anti-theft device wherein a code is entered into an electronic circuitry which when it matches a preselected code, will energize the ignition system or some other vital system of the automotive vehicle. One of the problems of systems which have been suggested heretofore is that a malfunction of the electronic circuitry for handling the coded information will stop the vehicle while it is operating, and so presents a very dangerous situation. Another problem of some prior art circuitries of the type with which we are concerned, is that their code can be deciphered by analyzing the conductors leading to the locked area from unlocked areas.
An object of the present invention is the provision of a new and improved vehicle anti-theft device wherein electrical switches are located in the operator compartment of the vehicle and must be actuated in proper sequence to transmit simple make or break functions through wires leading to electronic circuitry that is located in a locked area, and which in turn energizes the gate of a vehicle enabling silicon-controlled rectifier that remains actuated so long as current flows through the anode of the silicon-controlled rectifier, and regardless of what happens to the enabling circuitry of the gate.
Another object of the present invention is the provision of a new and improved anti-theft system that does not require a parking attendant to know or use any part of the logic system.
Another object is the provision of a new and improved anti-theft system wherein a minimum of power switches and circuitry is required.
Another object of the invention is the provision of a new and improved anti-theft system wherein the outputs of a plurality of switches are fed to logic circuitry housed in the locked area and wherein the circuitry outside of the locked area can not be tested to reveal the code necessary to actuate the system.
A further object of the present invention is the provision of a new and improved device of the immediately above described type wherein a make-break function of the switches in the operator compartment are directly connected to the clock terminals of flipflops which advance the actuating signal sequentially to the gate of a silicon-controlled rectifier and which resets the flipflops whenever they are actuated out of order, or another switch is actuated.
A still further object of the present invention is the provision of time delay means for a 4-switch sequence which makes the second, third and fourth switches of the sequence faster actuating than is the first switch.
Further objects and advantages of the invention will become apparent to those skilled in the art to which the invention relates from the following description of the preferred embodiments described with respect to the accompanying drawings.